This invention relates generally to automatically scaling or measuring the length of workpieces, and more particularly concerns the employment of heat to scale lengthwise elongated workpieces such as traveling pipe.
In the past, devices and methods for scaling workpieces required that the workpiece be metallic; that it be magnetizable; that the magnetized portion of the workpiece be erased (which in turn required the use of erase means); and that the workpiece be free or relatively free of surface contaminant so that suitable magnetization might be achieved. Examples of such techniques are found in U.S. Pat. Nos. 2,655,633 and 4,041,610. Disadvantages include the problem of remanent magnetization or other marking which desirably must be erased or otherwise removed so as to avoid confusion with marks or magnetization added during later scalings of the same workpieces such as pipes; the difficulty of erasing such magnetization or marks; and the problem of surface contaminant build-up on the work (such as oil, grease, dust, oxidation, on oil well pipe) which adversely affects or interferes with magnetization or marking capability. Accordingly, there is a need for simple apparatus and method for scaling long articles, which does not require erasing or removal of scaling marks or magnetization, and which is not adversely affected by work surface contaminants.